ABSTRACT

The preparation procedure was as follows (Zhang and Zhang, 2010; Wang et al., 2008). We mixed these three materials in a vessel in each of the five different ratios above, and then added the moderate isopropanol. We stirred the mixtures until the powdered ingredients formed into lumps, and then pressed them into slices with a tablet machine. The slices were placed in a vacuum drying oven and dried for six hours. Following this, the slices were removed from the oven and cut into pieces of equal size and weight (5 g) before immersion in H2SO4 solution for 12 hours. Finally, the slices were placed in 2 mol/L KCl aqueous solution ready for use.